Method and apparatus for producing pulp



Oct. 27, 1942.

E. T. TURNER METHOD AND APPARATUS FOR PRODUCING PULP 2 Sheets-Shed 1 Filed Nov. 16,;1938

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hi: ,4 r TURNEX Oct. 27, 1942. E. T. TURNER METHOD AND APPARATUS FOR PRODUCING PULP 2 Shets-Sheet 2 Filed Nov. 16, 19 38 Nw NR Patented Oct. 27,

- UNITED STATES PATENT OFFICE 2.800.184 maaa'rus roa PRODUCING Edward .T. Iurner, Dayton, Ohio Application November 16, 1938, Serial No. 20,753

scum. (cur-'1) tion to provide a system in which the material moves continuously through successive treatments from the raw stage to the finished stage.

A further object of the invention is to provide simple and eillcient means for maintaining the material under high pressure and at the desired temperature during the cooking operation.

A further object of the invention is to provide means for recirculating a portion of the liquid in a receptacle in which the material is being treated without recirculating the material or. interfering with its forward movement.

A further object of the invention is tc -provide I means for utilizing the heat and pressure energies of the cooked'material in the development of power.

Other objects the method and apparatus are described in detail.

In the accompanying drawings Fig. 1 is adiagrammatic view of anapparatus embodying my invention; and Fig. 2 is a-tic view of a similar apparatus showing a modified arrange- .ment of power mechanism.

In these drawings I have illustrated two embodiments' of the invention in which the pulp producing apparatus per se are the same but in which the power developing apparatus are slightly different. It will be understood, however, that these particular ts are for of the invention may appear as.

of the material will seat on the liquid and will accumulate in a pileabove the same. Liquid is continuously supplied to the upper portion of the tank and pr'eferablysprayed upon the pile of floating material therein. This liquid may be of any desired character and in the present instance it consists of a of water and chemical suitable for treating the particular material which is tobe reduced to pulp. In the arrangement here shown the water is conducted through a pipe 1 from a reservoir 8 preferably supported at a relatively high elevation with relation to the tank. Interpcsed in this-pipe is an injector s which is connected with a chemical'reservoir iii and by means of which the chemical is mixed with the water in the feed pipe 1. Both the pipe I and the connection between the injector and the chemical reservoir are provided with valves,

li' and-II, by means of which the relative proportions of water and chemical may be controlled. It is preferable to heat the water before. it is delivered to the tank and for this purpose the feed pipe 'I' is connected with a heater it, here shown as of the injector type. and steam is supplied tothis heater by a steam pipe, which may be connected with any suitable source oi steam. The mixture of steam and water are delivered from the heater I! through a conduit II to a' spray head it in the upper portion of the tank, this spray headbeing preferably annular inform and extending about a chute il in the top of thetank through which the material is delivered into thepurposeofillustrationonlyandthattheapparatus may take variousforms without departing'from the spirit obthe invention.

In carrying out my-lnvention I provide a r'e- .ceptacle 8, herein called a soak tank, which may conveniently be cylindric'al'in form and have a hopper shaped bottom I. ".flhis receptacle or tank is partially filled with liquid with which the material is to be lnitially treated. and thematerial is deposited in the upper portion of the tank and asitsinkstothebottomofthetankwiilbethoroughly soaked bythe time it reaches the bottom.

The material to be treated may take various forms, such as chips or straw, and when deposited the tank. The material vis preferably delivered to-the chute continuously asby means of an endless conveyor. I l but continuous delivery of ma terlal is not essential so long as it is delivered in such quantities and'at such intervalsas will provide a continuous supply of soaked material to the discharge end of the tank. -j

' It is desirable that a portion, r the liquid in the tank be recirculated through the same and in order to separate this liquid from the material and withdraw the same-for recirculation there is mounted in the lower part of the tank, preferably Just above the hopper shaped bottom I. a hollow screen ll. To minimise the tendency of this screen to clog it is preferably rotatable and polygonal in cross section. The screen extends substantially for the full width of the tank but is of relatively small diameter so that it does not materially obstruct the movement of the material through the tank. As here shown it is provided at one end with a shaft II which extends through a suifible bearing in the wall of the'tank and is inthetanklnadryconditionasubstantialpart connected with an'electric motor Ii by gearing 22. At itsother end the screen is rotatably supported on a pipe 23 which extends through the wall of the tank and into the hollow screen, preferably to a point near the center thereof. This pipe is connected at its outer end with the intake of a pump 24, the outlet of which is connected with a conduit 25 through whichthe liquid withdrawn from the interior of the screen is discharged into the heater l3 and thus returned to the tank. v

The soaked material is withdrawn from the bottom of the tank through a conduit 26 which is connected with the intake of a pump 21, and the outlet of the pump 21 is connected with a conduit 28 through which the soaked material and that portion of the liquid which is withdrawn therewith are delivered to a second receptacle or digester 29. This digester is in the form of a closed tank which also may be cylindrical in form and provided with a hopper shaped body 30. Means are provided for supplying steam under pressure to the digester and this steam may be supplied in any suitable manner. Preferably the steam is mixed with the soaked material and liquidin the conduit to preheat the same before they are delivered to the digester. In the present instance, steam is delivered from a suitable source of supply, through a pipe 33, to a heater 32 of the injector type which is interposed in the conduit 28 between the pump and the digester 29 to cause the steam to be intimately mixed with the material and liquid which are being forced through the conduit by the pump. The steam which is thus mixed with the material and liquid serves not only to initially heat the material but also maintain the material in .the digester at a high temperature and under high pressure, thereby materially ex-. pediting the cooking or digesting of the material. The temperature at which the material in the digester is maintained may be controlled by regulating the supply of steamto the injector so as to maintain the material at that temperature best adapted for cooking the same. A portion of the liquid in the digester is also recirculated and for this purpose the digester is provided with a hollow rotatable screen 34 and a pump 35 similar to the screen and pump for the soak tank but the discharge conduit 36 for the pump leads directly into the top of the digester. The pulp, consisting of a mixture of cooked material and liquid, is discharged from the lower portion of the digester through. a conduit 31 by the pressureof the steam within the digester and the rate of discharge may be controlled as by a valve 38 to retain the material in the digester for a length of time suflicient to v properly digest the same.

Thus the raw material after having been deposited in the upper portion of the soak tank moves slowly but continuously through the soak gested and is continuously discharged therefrom. This continuous operation results not only in increased production and in a reduction of the labor in connection with the treatments but also provides a more uniform quality of pulp.

The pulp, or mixture of material and liquid,

which is discharged from the digester may. be

disposed of in any suitable manner but this pulp is discharged at a high temperature and a high .where it may be connected with mechanism to the pulp is discharged through the expansion nozzle into the casing 40 where it engages and actuates the power element 4|. The impact of the pulp at high velocity with the blades of the power element not only actuates the power element but also serves to disintegrate the material, so that the latter is discharged from the casing in a finely divided form, through a discharge conduit 43 connected with the lower end of the casing. The steam, which in a large measure separates from the pulp in the casing 40 is withdrawn from the upper portion of the casing and, in the present instance, the steam is withdrawn through the steam pipe l4 and is utilized to preheat the liquid which is delivered through the expansion nozzle 44 an additional portion of the heat and pressure energies thereof is converted into velocity energy and acts on the power element 41 to actuate the latter. Steam is discharged from the upper portion of the casing 45 through a conduit 48 to a condenser 49, the action of which serves to maintain within the casing 45 a partial vacuum which materially increases the power derived from the velocity energy of the pulp. The pulp is withdrawn from the lower end of the casing 45 through a conduit 50 by means of a pump 5| which discharges the same through an outlet conduit 52 to a storage tank 53, or to such other point of discharge as may be desired. In order to maintain the partial vacuum in the casing 45 the pump is preferably located a substantial distance below the casing and a pressure head is maintained in the conduit to prevent air entering the casing through the conduit. To prevent the pressure head frombeing materially lowered by the action of the pump means have been provided for automatically regulating the discharge of pulp from the pump. For. this purpose the discharge conduit 52 of the pump is provided with a valve 54 which is actuated by a pressure operated device 55 connected by a tube 56 with the conduit 50, the arrangement being such that any substantial drop in the pressure in the conduit 50 will cause the pressure operated device 55 to close or partially close the valve 54, thus retarding the discharge of the pulp from the pump and enabling the pressure head in the conduit so to be restored.

. elements are actuated by the pulp discharged into the respective casings and, in the present instance, this is accomplished by by-passing a .portion of the pulp from the discharge conduit 31 of the digester to some point in the'apparatus beyond the second expansion nozzle 44. As here shown, a pipe 51 leads from the conduit 31 to the lower portion of the casing 45 and is provided with a valve 58 to control the flow of pulp through the same. This valve is actuated by a lever 59 which is operatively connected with a governor 60 which is driven by one or both of the power elements. In the present instance both power elements are mounted on the same shaft 42 and the governor is actuated by a shaft 6| connected with the shaft 4| by gearing 62, so that if the speed of the shaft 4| increases above a predetermined speed the governor will open the valve 58 and permit a portion of the pulp to flow directly from the conduit 31 to the lower portion of the casing 45.

In that form of apparatus shown in'Fig. 2 the pulp producing apparatus per se is identical with that shown in Fig. 1 and the same reference numerals have been applied thereto, but in this instance all the steam is utilized in developing power, thus providing an increased amount of power. In the arrangement shown the pulp is discharged from the digester through the conduit 31 and expansion nozzle 39 to a casing 62" in which is mounted a power element 63, the arin the same plant. However, if it is necessary to generate steam to preheat the feed liquid the cost of so generating steam would more than oii'set the value of the increased power derived from the arrangement shown in Fig. 2 and therefore the arrangement of Fig. 1 would be preferable. Thus the character, of the power generating mechanism selected will depend in a largemeasure at least upon the circumstances of the particular installation.

While I haveshown and described my method and one form of apparatus for performing the same, together with a minor modification thererangement being the same as that heretofore described. The steam which separates from the pulp in the casing 62 is delivered by a conduit 64 directly to a condenser 65, thereby producing a relatively high vacuum in the casing 62 which results in a substantial increase in the power developed by the power element. The pulp is withdrawn from the casing 62 through a conduit 66 tand pump 61 in the manner above described. If

\ lapejond power element is employed, as shown in Figifl, no steam would be withdrawn from the first casing but all the steam would pass with the material and liquid to the second casing and would be there used in developing power. The speed of the power element is regulated by bypassing a portion of the pulp about the power element and in this instance the by-pass conduit 68 leads from the discharge conduit 31 to the outlet conduit 69 of the pump 61. The by-pass valve 10 is controlled by a governor 1| which is actuated from the shaft 12 of the power element in the manner above described. With this arrangement of the power generating mechanism the single power element will develop a larger amount of power than will be developed by the two power elements in the arrangement shown in Fig. 1. In the arrangement of Fig. 1 a portion of the steam is withdrawn from the casing of the first power element and'is used to preheat the liquid for the soak tank and this reduces the amount of power which can be developed by that arrangement, while with-the single power element of Fig. 2 the steam is withdrawn directly to the condenser'so as to provide within the casing a relatively high vacuum and a-substantially increased power. when steam is available for preheating the liquid at a relatively small cost, such as exhaust steam, the arrangement of Fig. 2 is preferable because the increased power is secured at .no additional cost and can be utilized for various purposes either in connection with the operation of the present apparatus or with other apparatus 7 of, I wish it to be understood that I do not desire to be limited to the details thereof as various modifications may occur to a person skilled in the art.

Having now fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In a fibrous pulp producing apparatus, an upright receptacle having near its lower end a normally open outlet, means for introducing material and liquid into the upper portion of said.

receptacle and causing the same to move continuously toward said outlet, a hollow screen rotatably mounted in the lower portion of said receptacle and spaced from said outlet to separate a portion only of the liquid from said material, said screen being or such size and so arranged that material and liquid'may flow past the same continuously to said open outlet, .and means for withdrawing separated liquid from the interior of said screen and delivering the same to the upper portion of said receptacle.

2. In a fibrous pulp producing apparatus, a receptacle having near its lower end a normally open outlet, means for introducing material and liquid into the upper portion of "said receptacle and causing the same to move continuously toward said outlet, a hollow screen polygonal in cross section rotatably mounted in the lower portion of said receptacle above and spaced from said outlet, to separate a portion only of the liquid from said material, said screen being of such size and so arranged that material and liquid may flow past the same continuously to said open outlet. means for rotating said screen, a pump, means for connecting the intake ,of said pump with the interior of said screen to withdraw separated liquid therefrom, and a conduit leading from the outlet of said pump to the upper portion of said receptacle.

3. In a fibrous pulp producing apparatus, a receptacle, means for delivering material to the upper portion of said receptacleand mixing the mentioned receptacle and delivering the same to said second receptacle, means for supplying steam under pressure to the material delivered to said second receptacle to maintain the material and liquid therein at high temperature and high pressure to digest said material, a conduit leading from the lower portion of said second receptacle through which a mixture of digested material and liquid is continuously discharged at high temperature and h gh pressure, said conduit including an expansion nozzle in which a portion of said liquid is converted into steam and said steam expanded in and about said material and liquid to convert heat and pressure energies of said mixture into velocity energy, a. casing into which said expansion nozzle discharges said mixture at high velocity, a power element arranged in said casing to be actuated by the mixture of material, liquid and steam discharged from said expansion nozzle, means for continuously withrawing steam from said casing and delivering 7 he same to the first mentioned receptacle to heat the liquid and material therein, and means for discharging the material irom said casing.

4. In a iibrous pulp producing apparatus, a

digester, means for continuously delivering flbrous material and liquid to said digester, means ior supplying steam under pressure to the material delivered to said digester to maintain the material at high temperature and high pressure in said digester, a conduit leading from the lower portion of said dlgester through which a mixture of digested material and liquid is continuously discharged at'high temperature and high pres:- sure, said conduit including an expansion nozzle in which a portion of said liquid is converted into steam and said steam expanded in and about said material and liquid to convert heat and pressure energies of said mixtures into velocity energy, a casing into which said expansion nozzle discharges said mixture at high velocity, a power element arranged in said casing to be actuated by the mixture of material, liquid and steam discharged from said expansion nozzle, means for withdrawing steam from the upper portion of said casing, a conduit leading from the lower portion of said casing, a pump to withdraw material from said casing through the last mentioned conduit,

and means Ior automatically maintaining a pressure head in said last mentioned conduit above said pump.

5. The method of producing fibrous pulp which comprises soaking raw material in a relatively large quantity of liquid, separating a portion oi the liquid from the soaked material, continuously withdrawing soaked material and substantial quantities of unseparated liquid, continuously mixing steam with the withdrawn material and liquid and subjecting the mixture to pressure at high temperature to digest said material, continuously withdrawing digested material and liquid in a fluid mass, expanding said fluid mass to convert a portion of the liquid therein into steam and expanding. the steam to impart velocity energy to said fluid mass, converting velocity energy of said fluid mass into mechanical energy,'con-- tinuously separating the steam from said fluid mass and utilizing the separated steam to heat the liquid in which the raw material is soaked.

EDWARD T. TURNER. 

